tailieunhanh - Applications of High Tc Superconductivity Part 14

Tham khảo tài liệu 'applications of high tc superconductivity part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Superhard Superconductive Composite Materials Obtained by High-Pressure-High-Temperature Sintering 249 The critical field value Bcc for magnetic field parallel to c axis is about 3-4 T down to T 0 K Lyard et al. 2002 . The value of in plane critical magnetic field Ba in the ab plane is significantly higher and reaches 15-20 T at T 0 K. The anisotropy coefficient is equal Bcab Bcc 4-5. In the superconducting composite MgB2 Ce0-80 20 we measured superconducting transition at different magnetic fields. Fig. 10a . Using these data the temperature dependence of the critical magnetic field Bc was plotted in Fig. 10b. The temperature dependence of Bc is close to the same dependence in the initial MgB2 Lyard et al. 2002 Buzea Yamashita 2001 . Thus composite with 20 wt. of C60 has the same superconducting parameters as host MgB2. TÍKÌ Fig. 10. Temperature dependence resistance of R for MgB2 C60 - 80 20 wt. at different magnetic field a and temperature dependence of critical magnetic field Bc b that is similar to that of the initial MgB2. 250 Applications of High-Tc Superconductivity Superconductivity of heterofullerides Recently a method has been developed for synthesizing superconducting heterofullerides of the Fe and Cu groups with the composition K2MC60 Bulychev et al. 2004 . For example Fig. 11a shows the temperature dependence of the magnetic susceptibility X for fullerides with M Fe Ni Cu. Also shown in Fig. 11a is the x T curve for the well-known superconductor K3C60 for comparison. Superconducting heterofullerides of composition K2MC60 have lower superconducting transition temperatures Tc than K3C60 and the crystal lattice constant a of b Fig. 11. Temperature dependence of the magnetic susceptibility x of fullerides of composition K2MC60 M Fe Ni Cu and K3C60 for comparison upper and compounds RbCsTlC60 KCsTICo Rb2TlC60 down . Superhard Superconductive Composite Materials Obtained by High-Pressure-High-Temperature Sintering 251 the heterofullerides studied is .